In a ceremony at the event, Mr. Duffin signed an agreement with Igor I. Sechin, the head of the state-owned Rosneft, to expand its joint ventures to drill offshore in the Arctic Ocean, to explore for shale oil in Siberia and to cooperate on a liquefied natural gas plant in Vladivostok.

The deal came just weeks after the United States government imposed sanctions on the personal dealings — though not the corporate activities — of Mr. Sechin, a former military intelligence agent and longtime aide to President Vladimir V. Putin.

Despite the push by Western governments to isolate Moscow for its aggression in Ukraine, energy giants are deepening their relationships with companies here by striking deals and plowing more money into the country.

As President Vladimir V. Putin of Russia watched, David Campbell, BP's Russia chief, left, signed a preliminary agreement in May with Igor Sechin, president of Rosneft, right, to study shale oil deposits.Credit Sergei Karpukhin/Reuters